Mark Leo Listemann

Amine Catalyst Characterization by a Foam Model Reaction

olyurethane foams are prepared from the simultaneous reactions P of a diisocyanate with water and with a polymeric diol or polyol to form hydrogen-bonded urea (hard) segments and polyurethane networks (soft segments), respectively. The manufacture of a foam with a specific set of properties requires not only the proper choice of raw materials, but also the judicious use of catalysts, surfactants, and other additives. Requirements for catalysts and other additives are changing rapidly due to the phaseout of chlorinated fluorocarbons (CFCs) and the advent of increasingly stringent safety, health, and environmental regulations. The study of the chemistry of polyurethane foam formation is complicated by the heterogeneous nature of the reaction and the simultane-

The Influence of Silicone Surfactants on the Dispersion and Reactivity of Water in Flexible Slabstock Polyurethane Foam

In polyurethane foam formulations, the limited compatibility of water with polyol and isocyanate can lead to liquid-liquid dispersions, but the kinetic consequence of phase separation in these systems has been poorly understood. In the present study, the reagent compatibility and reactivity of model polyurethane formulations have been evaluated through a combination of ATR-FTIR spectroscopy, chemical titration, and optical microscopy. Kinetic experiments have revealed that phase separation reduces substantially the rate of water/isocyanate reaction. Using a reactive polyurethane model system, blowing and gelling reaction profiles for catalysts with and without the presence of surfactant were obtained. Mass loss rate-of-rise experiments on actual foam with and without surfactant were also conducted. Water titration experiments have indicated that silicone surfactants can induce phase separation of water, but do not effect the ultimate water solubility limit in the model formulations. Although the surfactants improve dispersion of reagents in these systems, no increases in reaction rates are observed in either model systems or actual foams.